Quote: Originally Posted by SMac770. You'd have to scan for DTCs. My driver's seat heater hasn't worked in a long time because the heater grid in the seat is broken, thus I have the DTC "heated seat (Z45), electrical fault in circuit". It could be something else for you, but you need to be able to scan DTCs to see what the car actually knows. What you see at 0.4 volts is the canbus trying to detect a bulb. When you plug in a known good bulb, the canbus should detect it, and then put a full 12v on the circuit. As far as I know, there is no fuse specific to numberplate lights. If you get 0.4v, then it indicates the circuit is good. The fuse locations are listed in your owner's manual. Keep in mind though, heated seats and power seats are generally on separate fuses. I would maybe unplug the seat module located under the seat and make sure it's all dry before plugging it back in. It should be a little black box located under the seat. Audi Original "S" Cars - Heated Seat Switch was hot last night - When driving last night I noticed the passenger side front seat heater switch was really hot to the tough. This morning I went to start the car but it wouldn't turn over. It sounds like the battery is drained. The passenger side switch is still hot to zk4juM.